The invention relates to an impregnating tool and a method of impregnating a reinforcing fiber material with a plastics material in a continuous process. The invention further relates to an apparatus for continuously manufacturing components, in particular, aircraft structural components, from fiber reinforced composite materials.
In aircraft construction, efforts are being made increasingly to use, as load-bearing components, components that are made entirely or partially of fiber reinforced composite materials, for example carbon fiber reinforced plastics (CRP). For example, DE 10 2007 062 111 A1 describes a crosspiece structure made of carbon fiber reinforced plastics material that is used to support the individual panels of an aircraft floor system for separating a passenger cabin from a cargo area disposed underneath the passenger cabin. It is further known, for example, from DE 10 2004 001 078 A1 and/or CN 100418850 to provide aircraft fuselage segments with a skin and reinforcing elements (for example frames, stringers) made of fiber reinforced composite materials.
When manufacturing aircraft structural components from fiber reinforced composite materials, first a multi-layer laminate is constructed from fiber prepregs. The fiber prepregs may comprise a woven or non-woven fabric made of reinforcing fibers, which are provided with a surface layer of an uncured plastics material, for example, an epoxy resin material. The laminate construction may be effected manually or in an automated manner. The fiber prepregs may then be brought into a desired shape of a planar portion forming an aircraft skin or of a reinforcing portion forming a frame or stringer. Finally, the plastics material applied onto the surfaces of the fibers is cured under pressure and/or raised temperature in an autoclave cycle, thereby producing a composite material having a matrix of a cured plastics material and reinforcing fibers embedded in the matrix. An autoclave process lends itself particularly well to the individual manufacture of components, even of a complex shape.
In contrast to this, EP 1 819 503 B1 describes a method of continuously manufacturing structural profiles that are suitable for use as aircraft structural components. In this method, first a multi-layer fiber layer structure is produced. For this purpose, dry fiber layers are unwound from appropriate rollers and supplied to a pre-forming tool that brings the fiber layers under pressure into a desired preliminary shape. The pre-formed fiber layer stack produced in the pre-forming tool is impregnated with a mixture of an epoxy resin and a hardening agent, in which, by supplying heat, a partial reaction that brings about a reduction of the viscosity of the resin is induced. In an intermittent press the resin-impregnated fiber layer stack is then heated further and put under pressure so that the resin gels and the crosslinking progresses to the point of dimensional stability. The complete curing of the resin is finally effected in a drying tunnel.
Throughout the process the fiber layers, the fiber layer stack and/or the resin-impregnated fiber layer stack are conveyed by means of appropriate take-off devices continuously to, and through, the individual stations of the process. The intermittent press is mounted movably so that over a specific section it may be moved jointly with the resin-impregnated fiber layer stack that is to be pressed. As soon as the treatment of a portion of the resin-impregnated fiber layer stack in the intermittent press has been completed, the intermittent press is opened and moved counter to the direction of motion of the resin-impregnated fiber layer stack until it reaches an appropriate position, in which the intermittent press may be closed again in order to treat a further portion of the resin-impregnated fiber layer stack. The continuous method described in EP 1 819 503 B1 is suitable for the large-scale manufacture of structural profiles with a constant cross section.